Recently a new type of semiconductor device that is capable of switching significant amounts of electric energy has become known. This device is a form of bilateral insulated gate field effect transistor. The device has a relatively low resistance drop to current flowing through the device, and the device is capable of bilateral current flow. The device is further capable of being switched from a conductive to a non-conductive, or a non-conductive to a conductive state by low power with the application of relatively low voltages. This type of device is shown in, for example, U.S. Pat. No. 4,148,046 issued on Apr. 3, 1979 to Hendrickson et al, U.S. Pat. No. 4,148,047 issued on Apr. 3, 1979 to Hendrickson, and in U.S. Pat. No. 4,152,714 to Hendrickson et al, issued on May 1, 1979.
The mode of switching the bilateral insulated gate field effect transistor centers on effectively short circuiting the gate of the insulated field effect transistor to the substrate of the device in order to turn the device completely off. The application of a potential to the gate which is greater than the threshold switching voltage for the device causes the device to switch into a full conductive mode. In a P-channel enhancement type of insulated gate field effect transistor, the most positive electrode is normally referred to as the source and the most negative the drain. In order to turn a bilateral insulated gate field effect transistor to the "on" state it is necessary to make the gate more negative than the source by at least the threshold voltage. This threshold voltage is normally in the neighborhood of 2 volts. In order to turn the device "off", it is necessary to connect the gate of the device to the substrate electrode of the device which for all practical purposes shorts the gate to the source.
The switching characteristics of the bilateral insulated gate field effect transistor are such that some unusual switching circuitry has been developed. The referenced co-pending application discloses a field effect transistor device means utilizing one or more insulated gate field effect transistor type switches operated from a single power source that is generally independent of any current flow through the substrate electrode element of the field effect transistor.